Mary-Kate and Ashley Olsen. Fred and George Weasley. Tia and Tamera Mowry. Let’s face it — society loves twins, and so do we. But most people don’t even know the coolest facts about twins, so let’s find out! We bet you didn’t know about most of these interesting tidbits . . . unless you’re a twin.

Twins can have different fathers: A rare situation called heteropaternal superfecundation can result in twins who have different fathers. If an ovulating woman has sex with two different men and releases multiple eggs during a certain period, she may conceive babies who share a womb but not a father.

The average twin birth weight is 5 pounds 5 ounces: Because twins tend to be delivered early, their weight at birth averages out to a relatively low 5 pounds 5 ounces.

Women can be predisposed to fraternal twins, not identical: The “twin gene”allows women to be genetically predisposed to conceiving fraternal twins, but identical twins are always the result of a random egg split.

Asia and Latin America have the lowest birthrates of twins: Not much is known about the reason, but Latin American and Asian countries produce the fewest number of twins per 1000 births.

Eighteen percent of identical twins have different dominant hands: If your identical twins indicate a different handedness from one another, they’re not alone — over 18 percent of their peers do the same.

Moms of twins live longer: In a study of naturally conceived twins that spanned from 1800 to 1970, records indicated that mothers of twins tended to live longer than mothers of singlets.

Almost half of all twins create their own language: To communicate with one another, around 40 percent of twins create an autonomous language that only they understand.

Massachusetts has the highest twin birthrate in the country:4.5 out of every 100 live births in Massachusetts are twins, compared to New Mexico, which has the lowest twin birthrate in the nation.

Women who eat dairy are more likely to conceive twins: In a study that compared vegan and nonvegan women’s pregnancies, researchers concludedthat women who eat dairy are about five times more likely to have twins than vegan women.

Belly buttons and fingertips are the best way to tell twins apart: Because belly-button shapes aren’t genetic (simply cut by a doctor) and fingerprints are determined by a baby’s placement in the womb, each are good indicators of a twin’s identity.

Twins begin to interact early in the second trimester: Twins have been documented intentionally interacting with one another as early as 14 weeks into a pregnancy — their special bond begins as fetuses!

Twins can be mirror images of one another: If identical twins develop facing one another, they may grow into mirror images. This could explain birthmarks on opposite sides, opposite handedness, and more.

The likelihood of having twins has increased more than 75 percent in three decades: Between 1980 and 2009, the American twin birthrate increased by 76 percent. If you’ve got a desire for twins, you’re in luck!